Create eap-inner-outer-reply policy

Create an easy-to-use policy that allows other policies to figure out whether to use reply or outer.reply in a call.

Use-Outer-Reply is an attribute only used in control, so it should be defined in dictionary.freeradius.internal (but I don't know which attribute number to give it), so I haven't defined one. 

If you can do this as a virtual attribute internally without using this policy, then so much the better, and feel free to reject this pull request.